IRF lidar

A lidar for aerosol and ozone studies in the troposphere/lower
stratosphere was funded by the Swedish Natural Science Research Council, NFR (Naturvetenskapliga forskningsrådet), in 2000.

Lidar is a technique for making measurements of the atmosphere from the ground.
The instrument for lidar measurements consists of two parts, an
emitter and a receiver. The emitter sends laser pulses into the
atmosphere. There the laser light gets scattered by particles and
molecules, partly also backwards to the lidar. There the receiver
detects the light which was scattered backwards. Since the speed of
light is constant, the time between the emission of the laser pulse and
detection at the receiver tells us at which height the light was
scattered. Changes in intensity can reveal clouds which are invisible
for the eye (but important for climate research).

Lidar in operation at IRF

After emission from the laser (right) the beam is expanded (center) to reduce divergence, before being deflected into the atmosphere (left).